Detect when document has completely loaded (including images)

Question

I have an HTML page with about 100 images. How can I detect when the page has completely loaded, including all images? I have been using the following code, and it seems to work in Chrome 80.

document.onreadystatechange = function () {
    if (document.readyState == "complete") {
        setTimeout(init, 10);
    }
}

However, Firefox 72 fires the init function right away. I can see the images as they pop in and are downloaded after the init function has fired. Is there a cross browser method to do what I need? Thanks.

I have tried window.onload, document.onreadystatechange and window.addEventListener('load', ...) already.

FYI, the image files are PNG format, but are embedded within an SVG file. And the SVG file is embedded within the HTML file. I can post a link if it is desired.

Edit: This is as minimal as I could get it.

<!DOCTYPE html>
<html>
    <head>
        <title>minimal reproducible example</title>
        <meta charset="UTF-8">
        <style>
body    {padding:0;margin:0;color:#ffffff;background-color:#404040;}
#cross  {z-index:2;position:fixed;left:50%;top:50%;visibility:hidden;}
#embed  {z-index:1;visibility:hidden;}
#load   {z-index:-1;position:fixed;display:inline-block;left:50%;top:50%;width:10em;margin-left:-5em;text-align:center;}
        </style>
        <script>
function init() {
    // in firefox 72 the embedded PNG images are loaded noticeably after the SVG image is made visible instead of before
    document.querySelector('#embed').style.visibility = 'visible';
    document.querySelector('#cross').style.visibility = 'visible';
}
window.onload = function () {
    setTimeout(init, 10);
}
        </script>
    </head>
    <body>
        <div id="load">Loading...</div>
        <svg id="embed" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="1024" height="1024" viewBox="0 0 1024 1024">
            <image width="1024" height="1024" x="0" y="0" xlink:href="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABAAAAAQABAMAAACNMzawAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAwUExURQAAAP///wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAFulh5UAAAAJcEhZcwAADsMAAA7DAcdvqGQAAApaSURBVHja7dqxDQNBEAMxt3D9N+sePhGwQ+VMJtbPzMzMzMzMzMzMzMzMzMzM7u59HH/DCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHFvZmZmZmZmZmZmZmZmZmZmB7c+JPBbL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9mZmZmZmZmZmZmZmZmZmZHdz6kMBvvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3ZmZmZmZmZmZmZmZmZmZmdnDrQwK/9QLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2Dcm5mZmZmZmZmZmZmZmZmZ2cGtDwn81gsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxb2ZmZmZmZmZmZmZmZmZmZge3PiTwWy9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvZmZmZmZmZmZmZmZmZmZmR3c+pDAb72AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY92ZmZmZmZmZmZmZmZmZmZnZw60MCv/UCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g3AsY9wLGvYBxL2DcCxj3Asa9gHEvYNwLGPcCxr2AcS9g0r/3B7oXJhneLUE8AAAAAElFTkSuQmCC" />
        </svg>
        <img id="cross" width="16" height="16" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsIAAA7CARUoSoAAAAAsSURBVDhPY2xoaPjPQAkAGQAEDORgkF4mqDlkg1EDRg0AgVEDGBgozM4MDAB7ETPvhopeAgAAAABJRU5ErkJggg=="/>
    </body>
</html>

What is supposed to happen:

Render gray screen with text "Loading..."
Small gray box appears at the same time (actually immediately after) large grid image is loaded

What happens in Firefox 72:

Render gray screen with text "Loading..."
Small gray box appears before the large grid image is loaded

Not sure how to slow things down enough so the difference is noticeable. You could try copy/paste-ing the large grid image 100 times, moving them to the right by 1024px each time.

Did you try the `.onload()` ? as in: `window.onload = () => console.log('window onload');` — blurfus, Feb 19 '20 at 06:38
Does this answer your question? [How to execute a function when page has fully loaded?](https://stackoverflow.com/questions/1033398/how-to-execute-a-function-when-page-has-fully-loaded) — blurfus, Feb 19 '20 at 06:39
instead of posting a link, can you post an [mcve]? does it work with a few images but it does not with 100? does it not work at all? (help us out a bit here) — blurfus, Feb 19 '20 at 06:45
I think you should go with explicit checks for img loading status, please check [this question](https://stackoverflow.com/questions/1977871/check-if-an-image-is-loaded-no-errors-with-jquery) — udalmik, Feb 19 '20 at 06:48
The PNG images are very large. In total they are ~40MB. The problem may not be noticeable in a minimal reproducible example. I will try to create one anyway. — posfan12, Feb 19 '20 at 06:55

Detect when document has completely loaded (including images)

0 Answers0